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Update Operations and Dealing with Constraint Violations
There are three basic operations to be executes on relations:
The INSERT Operation:
The insert operation permits us to insert a new tuple in a relation. When we try to insert a new record, then any of the following four types of constraints can be violated:
• Entity Integrity constraint: If the primary key attribute value of new tuple t is given as null.
Backward Recovery (UNDO): In this system the uncommitted changes made by a transaction to a database are undone. Instead the system is reset to the last consistent state of databa
Concurrency issues Data integrity: Threads accessing same object need to be synchronized, such as: banking account. Deadlock: One or more threads in system are perman
The JOIN operation is applied on two relations. When we want to choose related tuples from two given relation join is used. The join operation need that both the joined relations m
An instance of relational schema R (A, B, C) has distinct values of A including NULL values. then A is a candidate key or not? If relational schema R (A, B, C) has distinct val
Ask q“A database will be made to store information about patients in a hospital. On arrival, each patient’s personal details (name, address, and telephone number) are recorded wher
explain three types of internet risks to the consummers whent he business system is data dependent. how can we minimise these risks
What is the meaning of Data independence? Data independence means a programs that are not dependent on the physical attributes of data and a programs that are not dependent on
What are the advantages of object oriented databases in comparison with others? Why it is still not widely used? Object oriented designs are coherent, efficient and less prone
Which method is used to key transformation ? A hash method is used to key transformation.
Write short notes on relational model The relational model uses a collection of tables to show both data and the relationships between those data. The relational mo
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